Michelle Casados, age 10, of Huntington Beach, California, for her question:

What did little Pioneer learn about Jupiter?

Even space scientists win some and lose some. Comet Kohoutek was a dismal disappointment. But meantime, out by Jupiter, Pioneer 10 performed one of the greatest man made miracles that ever happened. For almost two years, the little space probe traveled through the Solar System to make a close up survey of the giant planet. And the mission was far, far more successful than anybody dared hope.

At its closest, Pioneer was only 83,000 miles from giant Jupiter, which is much closer than we are to the moon. Every moment, its busy instruments took records and relayed them back home. In two weeks during the close flyby, it relayed enough information to fill 60,000 pages of textbook material. Scientists need several months to sift and sort all these coded signals and assemble the results.

So we must wait a while for all the new information on Jupiter. At present we can report only a few of the surprises. For one thing, Jupiter's great globe is somewhat more flattened than was supposed. And the big planet sheds two and a half times more radiation than it gets from the sun    a mystery which may or may not be explained later. Thanks to Pioneer, we know that Jupiter is fairly warm and that its day and night temperatures are about equal. For some strange reason, some of its dense cloud belts are 15 degrees cooler than others. Pioneer also learned that the thick Jovian atmosphere contains some helium.

But the first big surprises were outside, around the big planet. Scientists half expected a forceful magnetic field and some hard radiation, maybe like Earth's Van Allen belts. Such fierce energies could damage the space probe's delicate instruments. The busy meters signaled that things were much, much worse than expected.

For a while, the waiting scientists almost gave up hope that Pioneer could survive. As it approached, the radiation grew strong enough to kill a person, then mounted to 1,000 times stronger. The space craft's safety margin dropped to one per cent. Then, just as all seemed lost, the little space traveler swerved and swooped away to safety traveling faster than any man made vehicle had ever traveled before.

Scientists are eager to translate the reports on the mysterious Great Red Spot and on many other features of the big planet and its moons. Thanks to Pioneer, we now know that the Jovian moon lo has an atmosphere and seems to be covered with an ice field, perhaps of frozen methane gas.

The greatest wonder was the flyby. It seemed logical that a spare craft could swerve around a planet and borrow gravitational energy to speed it on its way. Pioneer tested and proved this possible. Still relaying reports, it travels on to cross Saturn's orbit in 1976 and the orbit of Uranus in 1979. Then, as its instruments fade away, it heads out toward the constellation Taurus, carrying a plaque with a message from Earth. If all goes well, in 10 million years or so, it may deliver that message to some other populated planet in the Universe.